Gimbal mounting means and method

ABSTRACT

A gimbal mounting means for a control device having a frame and a control part to be operated by the gimbal mounting means, the gimbal mounting means comprising a first member pivotally mounted by pivot means to a frame and a second member pivotally mounted by pivot means to the first member at a right angle to the pivot mounting of the first member. Each pivot means comprises a ball carried by the respective member and being received in a cylinder member carried by either the other member or the frame for receiving the ball therein to provide substantially circular line contact for pivot movement therebetween, each cylinder member having another ball press fitted therein to be abutted by the pivot ball being received therein so that only point contact is provided therebetween in a thrust load direction.

United States Patent n91 Perkins Jan. 21, 1975 [75] Inventor: Charles H.Perkins, Richmond, Va.

[73] Assignee: Robertshaw Controls Company,

Richmond, Va.

22 Filed: Apr. 27, 1973 21 Appl. No: 355,060

[52] US. Cl. 308/2 R, 74/471 XY, 248/183 [51] Int. Cl. Fl6c 11/00 [58]Field of Search 308/2 R, 2 A; 74/55, 5 F.

OTHER PUBLICATIONS Product Engineering 7/5/65, Maurice Conklin pages 68& 69 Pivots Do Many Jobs."

Primary Examiner-Charles J. Myhre Assistant Examiner-R. H. LazarusAttorney, Agent, or FirmCandor, Candor & Tassone [57] ABSTRACT A gimbalmounting means for a control device having a frame and a control part tobe operated by the gimbal mounting means, the gimbal mounting meanscomprising a first member pivotally mounted by pivot means to a frameand a second member pivotally mounted by pivot means to the first memberat a right angle to the pivot mounting of the first member. Each pivotmeans comprises a ball carried by the respective member and beingreceived in a cylinder member carried by either the other member or theframe for receiving the ball therein to provide substantially circularline contact for pivot movement therebetween, each cylinder memberhaving another ball press fitted therein to be abutted by the pivot ballbeing received therein so that only point contact is providedtherebetween in a thrust load direction.

19 Claims, 6 Drawing Figures PATEHTED JAHZ 1 I975 SHEET 10F 2 FIG.1

PATENIH] JANE 1 I975 SHEET 2 OF 2 4o 59 e3 63' 3s GIMBAL MOUNTING MEANSAND METHOD This invention relates to an improved gimbal mounting meansand method for making such a gimbal mounting means or the like.

It is well known that a pair of concentrically disposed gimbal ringshave been pivotally mounted together with the outer ring being pivotallymounted to a frame means of a control device wherein the pivotalmovement of the rings is controlled by pneumatically operated movableparts of the control device so that the positioning of the gimbal ringswill control the position of a flapper valve member relative to a ventnozzle or the like. However, it has been found in such prior knowngimbal arrangement, no satisfactory means are provided for pivotallymounting the gimbal rings in a manner that will permit slightmisalignment of the pivot means and still provide for accurate operationof the rings and not non-linearity of movement as in the case of priorknown gimbal mounted rings.

Accordingly, it is a feature of this invention to provide an improvedgimbal mounting arrangement wherein slight misalignments between thepivot points of the pivotally mounted members can be readily compensatedfor without sacrificing accuracy of operation thereof.

Another feature of this invention is to provide a method for making sucha gimbal mounting means or the like.

In particular, one embodiment of this invention provides a controldevice having a frame and a gimbal mount carried thereby for operating acontrol part of the device and wherein the gimbal mount comprises afirst member pivotally mounted by pivot means to the frame and a secondmember pivotally mounted by pivot means to the first member at a rightangle to the pivot mounting of the first member. At least one of thepivot means means comprises means carried by the respective member forproviding substantially circular line contact for the pivot movementthereof and substantially point contact therewith for absorbing thrustloading therebetween. Such pivot means can comprise a pair of ballscarried by each pivot member on opposite sides thereof and beingrespectively received in cylinder means carried by the other member orthe frame where the pair of balls of each member make substantiallycircular line contact with the cylinder means during the pivot movementof the respective member. Each cylinder means has a ball initially pressfitted therein to be subsequently abutted by the pivot ball of the pivotmember being received therein so that substantially point contact isprovided therebetween in a thrust load direction therebetween.

Thus, if slight misalignment is provided between the pivot balls and thecylinder means receiving the same, a resulting circular line contact isstill provided by each pivot ball and its respective cylinder meansreceiving the same as well as point contact of the pivot ball with theball ofthe cylinder means whereby pivot movement of the pivot member isstill positively maintained along a straight line disposed between thecenters of the pivot balls of the respective pivot member.

Accordingly, it is an object of this invention to provide an improvedgimbal mounting means having one or more of the novel features set forthabove or hereinafter shown or described.

Another object of this invention is to provide a method for making sucha gimbal mounting means or the like.

Other objects, uses and advantages of this invention are apparent from areading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIG. I is a top view of a control device utilizing the gimbal mountingmeans of this invention.

FIG. 2 is an enlarged cross-sectional view taken substantially on line22 of FIG. 1.

FIG. 3 is a cross-sectional view taken substantially on line 3-3 of FIG.2.

FIG. 4 is a fragmentary, cross-sectional view taken on line 44 of FIG.3.

FIG. 5 is a fragmentary cross-sectional view taken on line 5-5 of FIG.3.

FIG. 6 is an exploded perspective view of the improved gimbal mountingmeans of this invention.

While the various features of this invention are hereinafter describedand illustrated as being particularly adapted to provide a gimbalmounting means for operating a flapper valve member, it is to beunderstood that the various features of this invention can be utilizedsingly or in any combination thereof to provide gimbal mounting meansfor other devices as desired.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to FIGS. I, 2 and 3, the improved control device of thisinvention is generally indicated by the reference numeral 10 andcomprises a frame structure or means 11 having two pressure chambers l2and 13 therein with each pressure chamber 12 and 13 being formed insubstantially the same manner whereby only the details of the pressurechamber 12 will be described with the understanding that suchdescription applies to the structure of the pressure chamber I3 exceptthat like parts of the pressure chamber 13 will be indicated by likereference numerals followed by a prime mark.

As illustrated in FIG. 2, the pressure chamber I2 is adapted to besupplied pressure fluid through an inlet 14 formed in the frame means 11and is partly defined by a tubular bellows construction 15 having itslower open end 16 secured to frame means II and its upper open end 1')closed by an outwardly flared flange 18 of a cup-shaped member I9disposed within the bellows construction 15 and having its end wall 20interconnected by a flexible tying means 21 to one end 22 of a pivotallymounted motion transmitting member 23 whereby up and down movement ofthe movable wall 20 causes clockwise and counterclockwise movement ofthe motion transmitting member 23 as will be apparent hereinafter.

A compression spring 24 has one end 25 bearing against the movable wall20 of the cup-shaped member 19 while the other end 26 thereof bearsagainst a spring retainer 27 that has its distance relative to themovable wall 20 controlled by a threaded adjusting member 28 carried bythe frame means II whereby the force of the compression spring 24 actingdownwardly on the wall 20 can be adjusted by the adjusting member 28. Inthis manner, as the pressure differential across the wall 20 increasesbecause of an increase in the pressure of the fluid being delivered tothe chamber [2, the resulting increased pressure differential across thewall 20 causes the wall 20 to move upwardly in H0. 2 in opposition tothe force of the compression spring 24 to cause a clockwise pivotingmovement of the motion transmitting member 23 whereby the other end 29of the motion transmitting member 23 moves downwardly in the drawingsand pulls downwardly on a tension spring member or mean 30 having itslower end 31 interconnected thereto. Thus, the tension spring member 30transmits such pivoting movement of the motion transmitting member 23 toa gimbal mount of this invention that is generally indicated by thereference numeral 32 in the drawings and which will be hereinafterdescribed, Conversely, a decrease in the pressure differential acrossthe movable wall 20 caused by a de' crease in the pressure of the fluidbeing delivered to the chamber 12 will cause the movable wall 20 to bemoved downwardly by the compression spring 24 and thereby causecounterclockwise movement of the motion transmitting member 23 so thatthe end 29 of the motion transmitting member 23 moves upwardly in H0. 2and, thus, moves the tension spring means 30 upwardly to operate thegimbal mount 32 as will be apparent hereinafter.

The motion transmitting member 23 is pivotally mounted to the framemeans H by a metallic flexure member 33 secured to the frame means 11 atits outer periphery 34 and secured to the motion transmitting member 23at its inner periphery 35 whereby pivoting movement of the motiontransmitting member 23 can take place because the flexure member 33 willflex between its inner and outer peripheries 3S and 34 to permit suchpivoting movement. A diaphragm seal member 36 is provided to the left ofthe flexure member 33 to seal the chamber 12 from the exterior of theframe means 11 at the flexure member 33.

Therefore, it can be seen that the motion transmitting members 23 and23' of the pressure chambers 12 and 13 are adapted to be pivoted bypressure changes in the respective chambers chambers 12 and 13 in themanner previously described.

The gimbal mount 32 of this invention comprises a pair of ring members37 and 38, the ring members 37 and 38 being concentrically disposed withthe ring member 37 being smaller in diameter than the outer ring member38 and being pivotally mounted thereto by a pair of like pivot meansthat are generally indicated by the reference numeral 39 so that theinner pivot ring 37 will pivot relative to the outer pivot ring 38 alonga pivot axis disposed substantially between the pivot means 39 that aredisposed substantially diametrically opposed each other relative to theinner pivot ring 37 whereby the pivot axis of its inner ring 37 issubstantially the same as a diameter thereof. The outer pivot ring 38,in turn, is pivotally mounted to the frame means 11 by a pair of likepivot means generally indicated by the reference numeral 40 along anaxis that is disposed along a line between the pivot means 40, suchpivot line being substantially the same as a diameter of the outer ring38 that is disposed substantially at right angles to the pivot axisprovided by the pivot means 39 for the inner pivot ring 37.

The tension spring means 30, that has its lower end 31 interconnected tothe end 29 of the motion transmitting member 23, has its upper end 41secured to a threaded member 42 threaded into a threaded bore 43 formedin the inner annular ring 37 whereby pivoting movement of the motiontransmitting member 23 causes pivoting movement of the inner annularring 37 about the pivot means 39. Similarly, the end 29' of the motiontransmitting member 23' for the pressure chamber 13 is interconnected tothe lower end 31' of a motion transmitting tension spring means 30' thathas its upper end 41' secured to a threaded member 42' secured in athreaded bore43' formed in the outer gimbal ring 38 in the mannerillustrated in FIG. 4 whereby pivoting movement of the motiontransmitting member 23' causes the outer gimbal ring 38 to pivot on itspivot means 40.

The inner pivot ring 37 has an outer cylindrical wall 44 and an innerangularly disposed wall 45 that termi nates in substantially a knifeedge 46 adapted to engage against a reduced end 47 of a resilientflapper valve member 48 having the other end 49 thereof secured to theframe means 11 by fastening members 50. The end 47 of the flapper valvemember 48 is disposed over a vent nozzle 51 of the control device 10whereby the amount of fluid venting through the nozzle 51 is controlledby the position of the flapper valve member 48 relative thereto, theflapper valve member 48 having a natural resiliency that tends to movethe flapper valve member 48 into full seating on the nozzle 51 toprevent any fluid flow therethrough. Thus, the pivotal movement of thegimbal mount 32 by the pressure means 12 and 13 in a manner hereinafterdescribed controls the position of the flapper valve member 48 relativeto the nozzle 51 and, thus, the amount of venting through the nozzle 51in a manner well known in the art.

However, as previously stated, this invention provides improved means 39and 40 for pivotally mounting the gimbal rings 37 and 38 and will now bedescribed.

Each pivot means 39 and 40 includes a cylinder means 52 that isexternally threaded at 53 and has a cylindrical bore 54 coaxiallyinterrupting one end 55 thereof and terminating therein to define a flatend wall 56 spaced from the end 55 a certain amount as will be apparenthereinafter.

The other end 57 of each cylinder means 52 is provided with a slot 58disposed diametrically across the same for receiving a screw driver orthe like to permit rotational movement of the respective cylinder member52 in an axial manner toward and away from its re spective gimbal ring38 or 37. For example, the two cylinder means 52 for the pivot means 40for the outer gimbal ring 38 are respectively threadedly disposed inthreaded bores 59 formed in the frame means I] as illustrated in FIG. 3whereby the cylinder means 52 for the pivot means 40 are adapted to beaxially moved toward and away from the gimbal ring 38 along a line thatrepresents a diameter of the gimbal ring 38.

In regard to the pivot mounts 39 for the inner gimbal ring 37, thecylinder means 52 therefor are respectively threadedly disposed inthreaded bores 60 formed in an aligned manner through opposed cylinderwalls 61 and 62 of the outer ring 38 whereby the cylinder means 52carried by the outer gimbal ring 38 are adapted to be axially movedalong a line corresponding to a diameter of the inner ring 37 that isdisposed at substantially a right angle to the diameter of the outerring 38 along which the cylinder means 52 for the pivot means 40 areaxially movable.

Each cylinder defining means 52 initially has a spherical metallic ball63 press fitted into the bore 54 thereof so as to be disposed againstthe end wall 56 as illustrated, the diameter of the ball 63 beingslightly larger than the initial diameter of the bore 54 so that duringthe press fitting of the ball 63 in the bore 54 of the respectivecylinder means 52, such movement of the ball 63 from the exterior of thebore 54 to abut against the end wall 56 of the bore 54, in effect, sizesand burnishes the bore 54 for a purpose hereinafter described eventhough the ball 63 remains firmly against the end wall 56 through thepress fit relation thereof with the bore 54 of the cylinder means 52 fora purpose hereinafter described.

The pivot means 40 for the outer gimbal ring means 38 includes a pair ofmetallic balls 63' identical to the balls 63 previously described andrespectively secured to the outer cylindrical wall 61, such as bywelding, as illustrated in FIG. 6 so that the same are adapted to bereceived in the bores 54 of the cylinder means 52 of the pivot means 40in the manner illustrated in FIG. 3 when the ring 38 is assembled to theframe means 11 whereby the secured balls 63' will make substantiallycircular line contact with the cylinder means 52 at the bores 54 thereoffor pivotal movement of the ring 38 substantially along a line drawnthrough the centers of the secured balls 63' while the balls 63'respectively make only point contact with the balls 63 of the cylindermeans 52 in any thrust loading direction along the pivot line of theouter ring 38.

Similarly, a pair of balls 63" are secured to the outer cylindrical wall44 of the inner ring 37 in a manner to be received in the bores 54 ofthe cylinder means 52 carried by the outer ring 38 in the mannerillustrated in FIG. 3 as to provide circular line contact with thecylinder means 52 of the pivot means 39 whereby the inner ring 37 willpivot along a line disposed substantially between the centers of theballs 63". Also, the balls 63" of the inner ring 37 merely make pointcontact with the balls 63 of the cylinder means 52 of the pivot means 39in any thrust loading direction along the pivot line for the inner ring37.

It is preferred that the length of the bores 54 be so sized relative tothe balls 61 and that the cylinder means 52 be so adjusted that thesecured balls 63' and 63" will be received in the respective bores 54 ofthe cylinder means 52 a distance greater than the radius of the balls63' and 63", but a distance less than the diameter of the balls 63' and63".

In this manner, it can be seen that the gimbal rings 37 and 38 may bereadily assembled to the frame means ll by the respective pivot means 39and 40 and be interconnected to the motion transmitting members 23 and23' by the tension spring means 30 and 30' to operate in a manner now tobe described.

As the motion transmitting member 23 is pivoted in a counterclockwisedirection by the pressure differential acting across the movable wall ofthe pressure chamber 20 decreasing, such upward movement of theright-hand end 29 of the motion transmitting member 23 causes thetension spring 30 to move upwardly and cause the inner gimbal ring 36 topivot on its pivot means 39 in a manner to raise the end 47 of theflapper valve member 48 relative to the vent nozzle 51 to increase thevent flow therethrough. Conversely, as the pressure differential acrossthe movable wall 20 of the pressure chamber 12 increases, the movablewall 20 moves upwardly in FIG. 2 and causes the motion transmittingmember 23 to pivot in a clockwise direction whereby the tension spring30 pivots the inner gimbal ring 37 on its pivot means 39 in a manner topermit the flapper valve member 48 to move closer to the vent nozzle 51and thereby decrease the fluid flow therethrough. Similarly, an increasein pressure in the pressure chamber 13 causes the motion transmittingmember 23' to pivot in a clockwise direction in FIG. 6 and thereby causethe outer gimbal ring 38 to pivot on its pivot means 40 in such a mannerthat the inner gimbal ring 37 being carried thereby permits the flappervalve member 48 to move closer to the vent nozzle means 51 and therebydecrease the fluid flow therethrough. Conversely, a decrease in pressurein the pressure chamber 13 causes the motion transmitting member topivot in a counterclockwise direction in H0. 6 and thereby pivot theouter gimbal ring 38 on its pivot means 40 in a manner to cause theinner ring 37 to move the flapper valve member 48 away from the ventnozzle 51 to increase the fluid flow therethrough.

Thus, it can be seen that the pivot means 39 and 40 of this inventionreadily permit the gimbal rings 37 and 38 to pivot in the mannerpreviously described for operating the flapper valve member 48.

Further, because the line of contact between the pivot balls 63' and 63'and their respective cylinder members 52 is always circular, slightmisalignment of the axes of the cylinder means 52 and the axes of therings 37 and 38 defined by a line drawn between the centers of therespective pair of balls 63' and 63" secured thereto is accommodatedwithout increasing bearing clearance since the bearing contact is alwayscircular and the bearing circle can be freely positioned in spacewithout changing the end play of the bearing structure. Thus. in effect,each pair of ball pivots acts as a universal joint, when adjusted.

Therefore, it can be seen that this invention not only provides animproved gimbal mounting means for a control device or the like, butalso this invention pro vides an improved method for making such agimbal mounting means or the like.

While the form and method of the invention now preferred have beendisclosed and illustrated as required by the Patent Statute, it is to beunderstood that other forms and methods can be utilized and still comewithin the scope of the appended claims.

What is claimed is;

1. in a control device having a frame and a gimbal mount carried therebyfor operating a control part of said device and wherein said gimbalmount comprises a first member pivotally mounted by pivot means to saidframe and a second member pivotally mounted by pivot means to said firstmember at a right angle to the pivot mounting of said first member, theimprovement wherein at least one of said pivot means comprises meanscarried by the respective member for providing substantially circularline contact for the pivot movement thereof, said one pivot means alsocomprising means cooperating with said means of said respective memberto provide substantially point contact therebe tween for thrust loadabsorbing purposes, said contact being spaced from said circular linecontact.

2. in a control device as set forth in claim 1 wherein said means forproviding substantially circular line contact comprises ball meanscarried by the respective member.

3. In a control device as set forth in claim I, said respective membercomprising said first member, said means for providing substantiallycircular line contact comprising a pair of balls disposed on oppositesides of said member and a pair of cylinder means carried by said frameand respectively receiving said balls therein.

4. In a control device having a frame and a gimbal mount carried therebyfor operating a control part of said device and wherein said gimbalmount comprises a first member pivotally mounted by pivot means to saidframe and a second member pivotally mounted by pivot means to said firstmember at a right angle to the pivot mounting of said first member, theimprovement wherein at least one of said pivot means comprises meanscarried by the respective member for providing substantially circularline contact for the pivot movement thereof, said one pivot meanscomprising means cooperating with said means of said respective memberto provide substantially point contact therebetween for thrust loadabsorbing purposes, said means of said respective member comprising ballmeans and said means of said one pivot means cooperating therewithcomprising ball means for being disposed in contact with said firstnamed ball means.

5. ln a control device as set forth in claim 4, said one pivot meanscomprising cylinder means having said ball means received thereinwhereby said ball means of said respective member is adapted to rotaterelative to said cylinder means to provide substantially circular linecontact therewith.

6. in a control device as set forth in claim 5, said ball means of saidpivot means having been press fitted in said cylinder means before saidball means of said respective member has been received in said cylinder,

7. in a control device as set forth in claim 6, said cylinder meansbeing axially adjustable toward and away from said ball means of saidrespective member.

8. ln a control device having a frame and a gimbal mount carried therebyfor operating a control part of said device and wherein said gimbalmount comprises a first member pivotally mounted by pivot means to saidframe and a second member pivotally mounted by pivot means to said firstmember at a right angle to the pivot mounting of said first member, theimprovement wherein at least one of said pivot means comprises meanscarried by the respective member for providing substantially circularline contact for the pivot movement thereof. said respective membercomprising said first member, said means for providing substantiallycircular line contact comprising a pair of balls disposed on oppositesides of said member and a pair of cylinder means carried by said frameand respectively receiving said balls therein, and another pair of ballsrespectively disposed in said cylinder means and respectively beingabutted by said balls of said first member so that substantially pointcontact is provided therebetween in a thrust load direction.

9. In a control device as set forth in claim 8, said first membercarrying another such pair of cylinder means respectively having a pairof balls therein, said second member having a pair of balls carriedthereon on opposite sides of said second member and respectivelyreceived in said cylinder means of said first member to providesubstantially circular line contact therewith for the pivot movementthereof and respectively abutting said balls of said cylinder means ofsaid first member so that substantially point contact is providedtherebetween in a thrust load direction.

10. In combination, a first member, and a second member pivotallymounted to said first member by pivot means, said pivot means comprisinga pair of balls carried by said second member on opposite sides thereofand a pair of cylinder means carried by said first member andrespectively receiving said balls therein whereby said second member isadapted to pivot on an axis defined by a substantially straight linepassing through the centers of said balls while said balls respectivelymake substantially circular line contact with said cylinder means, saidballs also respectively making point contact with said cylinder means inspaced relation to said circular line contact therewith.

II. A combination as set forth in claim 10 wherein said cylinder meanseach comprises a threaded adjust ing member threadedly carried by saidfirst member whereby said cylinder means can be axially adjusted towardand away from said balls of said second member 12. in combination, afirst member, and a second member pivotally mounted to said first memberby pivot means, said pivot means comprising a pair of balls carried bysaid second member on opposite sides thereof and a pair of cylindermeans carried by said first member and respectively receiving said ballstherein whereby said second member is adapted to pivot on an axisdefined by a substantially straight line passing through the centers ofsaid balls while said balls respectively make substantially circularline contact with said cylinder means, and a second pair of ballsrespectively disposed in said cylinder means to be carried thereby. saidsecond pair of balls respectively being abuttcd by the first named pairof balls whereby substantially point contact is provided therebetween ina thrust load direction,

13. A combination as set forth in claim 12 wherein said second pair ofballs are press fitted into said cylinder means.

14. A combination as set forth in claim 12 wherein said first-named pairof balls each is disposed in said cylinder means a distance less thanthe diameter of the respective ball but greater than the radius thereof.

15. A method for pivotally mounting a second member to a first membercomprising the steps of securing a pair of balls to opposite sides ofsaid second member, securing a pair of cylinder means to said firstmember. and disposing said balls respectively in said cylinder meanswhereby said second member is adapted to pivot on an axis defined by asubstantially straight line passing through the centers of said ballswhile said balls re spectively make substantially circular line contactwith said cylinder means as well as point contact with said cylindermeans in spaced relation to said circular line contact therewith.

16. A method as set forth in claim 15 and including the step of formingsaid cylinder means each from a threaded adjusting member so as to bethreadably carried by said first member whereby said cylinder means canbe axially adjusted toward and away from said balls of said secondmember.

17. A method for pivotally mounting a second member to a first membercomprising the steps of securing a pair of balls to opposite sides ofsaid second member, securing a pair of cylinder means to said firstmember. disposing said balls respectively in said cylinder means wherebysaid second member is adapted to pivot on an axis defined by asubstantially straight line passing through the centers of said ballswhile said balls respectively make substantially circular line contactwith said cylinder means, and disposing a second pair of ballsrespectively in said cylinder means to be carried thereby 19. A methodas set forth in claim 17 wherein said step of disposing said first namedballs into said cylinder means comprises the step of disposing saidfirst named pair of balls respectively in said cylinder means a distanceless than the diameter of the respective ball but greater than theradius thereof.

1. In a control device having a frame and a gimbal mount carried thereby for operating a control part of said device and wherein said gimbal mount comprises a first member pivotally mounted by pivot means to said frame and a second member pivotally mounted by pivot means to said first member at a right angle to the pivot mounting of said first member, the improvement wherein at least one of said pivot means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof, said one pivot means also comprising means cooperating with said means of said respective member to provide substantially point contact therebetween for thrust load absorbing purposes, said contact being spaced from said circular line contact.
 2. In a control device as set forth in claim 1 wherein said means for providing substantially circular line contact comprises ball means carried by the respective member.
 3. In a control device as set forth in claim 1, said respective member comprising said first member, said means for providing substantially circular line contact comprising a pair of balls disposed on opposite sides of said member and a pair of cylinder means carried by said frame and respectively receiving said balls therein.
 4. In a control device having a frame and a gimbal mount carried thereby for operating a control part of said device and wherein said gimbal mount comprises a first member pivotally mounted by pivot means to said frame and a second member pivotally mounted by pivot means to said first member at a right angle to the pivot mounting of said first member, the improvement wherein at least one of said pivot means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof, said one pivot means comprising means cooperating with said means of said respective member to provide substantially point contact therebetween for thrust load absorbing purposes, said means of said respective member comprising ball means and said means of said one pivot means cooperating therewith comprising ball means for being disposed in contact with said first named ball means.
 5. In a control device as set forth in claim 4, said one pivot means comprising cylinder means having said ball means received therein whereby said ball means of said respective member is adapted to rotate relative to said cylinder means to provide substantially circular line contact therewith.
 6. In a control device as set forth in claim 5, said ball means of said pivot means having been press fitted in said cylinder means before said ball means of said respective member has been received in said cylinder.
 7. In a control device as set forth in claim 6, said cylinder means being axially adjustable toward and away from said ball means of said respective member.
 8. In a control device having a frame and a gimbal mount carried thereby for operating a control part of said device and wherein said gimbal mount comprises a first member pivotally mounted by pivot means to saiD frame and a second member pivotally mounted by pivot means to said first member at a right angle to the pivot mounting of said first member, the improvement wherein at least one of said pivot means comprises means carried by the respective member for providing substantially circular line contact for the pivot movement thereof, said respective member comprising said first member, said means for providing substantially circular line contact comprising a pair of balls disposed on opposite sides of said member and a pair of cylinder means carried by said frame and respectively receiving said balls therein, and another pair of balls respectively disposed in said cylinder means and respectively being abutted by said balls of said first member so that substantially point contact is provided therebetween in a thrust load direction.
 9. In a control device as set forth in claim 8, said first member carrying another such pair of cylinder means respectively having a pair of balls therein, said second member having a pair of balls carried thereon on opposite sides of said second member and respectively received in said cylinder means of said first member to provide substantially circular line contact therewith for the pivot movement thereof and respectively abutting said balls of said cylinder means of said first member so that substantially point contact is provided therebetween in a thrust load direction.
 10. In combination, a first member, and a second member pivotally mounted to said first member by pivot means, said pivot means comprising a pair of balls carried by said second member on opposite sides thereof and a pair of cylinder means carried by said first member and respectively receiving said balls therein whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circular line contact with said cylinder means, said balls also respectively making point contact with said cylinder means in spaced relation to said circular line contact therewith.
 11. A combination as set forth in claim 10 wherein said cylinder means each comprises a threaded adjusting member threadedly carried by said first member whereby said cylinder means can be axially adjusted toward and away from said balls of said second member.
 12. In combination, a first member, and a second member pivotally mounted to said first member by pivot means, said pivot means comprising a pair of balls carried by said second member on opposite sides thereof and a pair of cylinder means carried by said first member and respectively receiving said balls therein whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circular line contact with said cylinder means, and a second pair of balls respectively disposed in said cylinder means to be carried thereby, said second pair of balls respectively being abutted by the first named pair of balls whereby substantially point contact is provided therebetween in a thrust load direction.
 13. A combination as set forth in claim 12 wherein said second pair of balls are press fitted into said cylinder means.
 14. A combination as set forth in claim 12 wherein said first-named pair of balls each is disposed in said cylinder means a distance less than the diameter of the respective ball but greater than the radius thereof.
 15. A method for pivotally mounting a second member to a first member comprising the steps of securing a pair of balls to opposite sides of said second member, securing a pair of cylinder means to said first member, and disposing said balls respectively in said cylinder means whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circuLar line contact with said cylinder means as well as point contact with said cylinder means in spaced relation to said circular line contact therewith.
 16. A method as set forth in claim 15 and including the step of forming said cylinder means each from a threaded adjusting member so as to be threadably carried by said first member whereby said cylinder means can be axially adjusted toward and away from said balls of said second member.
 17. A method for pivotally mounting a second member to a first member comprising the steps of securing a pair of balls to opposite sides of said second member, securing a pair of cylinder means to said first member, disposing said balls respectively in said cylinder means whereby said second member is adapted to pivot on an axis defined by a substantially straight line passing through the centers of said balls while said balls respectively make substantially circular line contact with said cylinder means, and disposing a second pair of balls respectively in said cylinder means to be carried thereby so that said second pair of balls are respectively abutted by the first named pair of balls whereby substantially point contact is provided therebetween in a thrust load direction.
 18. A method as set forth in claim 17 and including the step of press fitting said second pair of balls respectively into said cylinder means.
 19. A method as set forth in claim 17 wherein said step of disposing said first named balls into said cylinder means comprises the step of disposing said first named pair of balls respectively in said cylinder means a distance less than the diameter of the respective ball but greater than the radius thereof. 